The invention described herein was made in the performance of work under NASA Contract No: NCC8-115 and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958 (42 U.S.C. 2457).
1. Field of the Invention
The invention relates to the field of anti-vortex baffle systems for propellant tanks and the like and, in particular, to a combination anti-vortex baffle assembly and filter having a large flow area and simple construction.
2. Description of Related Art
In a vehicle such as a spacecraft booster, it is well known that when propellant is rapidly drained from the tanks, a vortex can sometimes form. This may result in vapor entering into the propellant feed line and possibly into the turbo-pump causing cavitation, which can cause damage thereto or even an explosion. To eliminate this possibility, anti-vortex baffling arrangements are used. For example, in U.S. Pat. No. 2,920,648 "Device To Eliminate Vortices In Fuel Tanks" by R. M. Seffer, a flat disc having "egg-crate" like partitions therein is movably mounted within the tank and travels down the longitudinal axis thereof as it is emptied of propellant. The disadvantages of such a design are obvious: if the tank is large, there is a significant weight penalty; and because it is complicated there is possible reliability issue. In U.S. Pat. No. 2,946,345 "Baffle Structure For Tanks" by W. W. Weltmer, a pyramid shaped structure is located at the bottom of the tank composed of a series of "elbow" shaped vanes. While the structure would work, it is composed of a large number of small parts, making it expensive to manufacture and install.
U.S. Pat. Nos. 5,293,895 and 5,279,323 both titled "Liquid Management Apparatus For Spacecraft" by R. K Grove, et al., disclose a more conventional approach of perforated ribs mounted to the tank wall extending along the longitudinal axis thereof. At the bottom of the tank, the ribs extend radially inward toward the center thereof. A central beam is included that also extends along the longitudinal axis incorporating perforated "cross" shaped ribs. A filter screen is positioned below the ribs covering the outlet port at the bottom of the tank. Here the effect of the baffles is obvious and the screen is of the type that when wetted prevents gas from leaving the tank. However, the structure is heavy and complicated and the filter is not readily accessible for cleaning. Other examples of the use of a screen to prevent gas from entering the propellant feed lines are found in U.S. Pat. No. 4,768,541 "Means Of Expelling Parallel Tanks To Low Residuals" by P. E. Uney, et al. and U.S. Pat. No. 4,743,278 "Passive Propellant Management System" by T. Yeh.
An additional problem is that contamination in the propellant tank may also be drawn into the turbo-pumps causing damage. But most filter designs increase flow resistance, which is highly undesirable. In addition, since most boosters are expendable, the filters in the propellant tanks are not designed for easy access for cleaning, which is a requirement for a reusable launch vehicle.
Thus, it is a primary object of the invention to provide an anti-vortex baffle assembly for a propellant tank.
It is another primary object of the invention to provide an anti-vortex baffle assembly for a propellant tank that incorporates a filter.
It is a further object of the invention to provide an anti-vortex baffle assembly for a propellant tank that incorporates a filter and that does not restrict propellant flow.
It is a still further object of the invention to provide an anti-vortex baffle/filter assembly for a propellant tank that is simple to manufacture.
It is another object of the invention to provide an anti-vortex baffle/filter assembly for a propellant tank incorporating a filter that can be easily removed for repair and cleaning.